Antibacklash device



Manch 11, 1947.

W. E. SWlFT,' JR

ANTIBACKLAS H DEVICE Original Filed March 20, 1944 Elma/14M Wmnrd E- 2111 111111 Reissued Mar. 11, 1947 UNITED STATES PATENT OFFICE AN TIBACKLASH DEVICE Willard E. Swift Jr., Worcester, Mass.

Original No. 2,372,693, dated April 3, 1945, Serial No. 527,353, March 20, 1944. Application for reissue March 33, 1946, Serial No. 658,367

11 Claims. 1

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon,

The present invention pertains to a novel antibacklash device for a driven member in relation to its driving member. The principal object of the invention is to provide a mechanism whereby the position of the driven member remains fixed, without play, after the driving member has come to rest. Backlash or play in the driving operation is immaterial.

One of the applications of the invention occurs, for example, in the traversing of a gun, where it is highly desirable that the adjusted position of the gun shall remain fixed. The stated object of the invention is accomplished generally by the use of a clutch in the form of a helical spring enclosing one or both shafts and normally expanded against an enclosing fixed member, with one end of the spring anchored to the driven shaft. The driven shaft is thereby fixed or locked. On rotation of the driving shaft in the direction in which the spring is wound from its anchored end, an appropriate driving connection engages the free end of the spring and contracts it away from the enclosing member. The, driven shaft is thereby released for rotation, and rotation is effected by the engagement of abutting parts of the driving and driven shafts. the driving force, the spring is free to expand into clutching or looking engagement with the fixed enclosing member, and the driven shaft is thereby also locked inasmuch as it is anchored to the spring.

A dual system of this character arranged on the shafts in such a manner that one part thereof operates in the opposite direction of the other part, permits the driven shaft to be propelled in either direction and secures the same shaft against 4 Figure 4 is a detail section of one of the adjustable teaser lugs.

The driving member or shaft is formed with two longitudinally extending circumferentially spaced driving lugs 2 and 3. 'The driving lug 2 is formed near each end with an outwardly. ex-

On cessation of tending so-called teaser lug 4 or 4' for a purpose that will presently be. described.

The driver1 member or shaft 5 is alined with the driving shaft and is formed with a pair 'of longitudinal slots 6 receiving the driving lugs 2 and 3 and forming a pair of abutments 1. and -8 between the lugs.

The driven shaft. carries a spring anchoring collar 10 fastened to the driven shaft by suitable means such as screws Ii. At the ends of the collar are disposed two coil springs I2 and i3 surrounding the driven shaft and wound in the same direction thereon. The inner end of each spring is fastened to the collar 10, for example, by means of an extremity l4 fitted closely in a notch i5 cut in the adjacent end of the collar.

At the outer end of the springs are mounted end collars l5 and ii. notched at l8 to receive the bent or hooked end [90f the corresponding spring.

. The outer edge of each collar I6, I1 is formed with a notch 20 which loosely receivesthe corresponding teaser lug 4 or 4'. The springs l 2 and I3 are normally expanded against a fixed enclosing element 2|.

For the purpose of describing the operation of the, device, it may be assumed that in the idle position the lugs 4 and 4? are substantially in contact with opposite ends, respectively, of. the corresponding slots 20, In this position of the parts, the driving lugs 2 and .3. are slightly spaced from abutments I and 8 and approximately centrally disposed therebetween as indicated at 22-, 23, 26, 21. Even if the lugs 4 should be slightly spaced from theaforementioned ends of the slots 20 rotation of the driving shaft in either direction will bring one of the lugs 4 and 4 into engagement with theend of the corresponding slot 20 before the associated driving lug 2, or 3 engages the abutment adjacent thereto in the direction of rotation.

If the driving shaft is rotated clockwise with respecttoFigure 2, the teasing lug 4 on driving lug 2 will engage an end of the slot 20, in collar IB' and dra the end- I9 of the engaged spring in the contracting direction, since the other end of the spring is connected directly tothe load through the anchoring collar I0 fastened to the driven shaft. Contraction of the spring, l2 in this manner obviously releases it from the stationary element 2|. Therelative movement between the collars "Sand [,0 in the contraction of the spring I2 is sufficient to bring the driving lugs 2 and 3 into driving engagement withthe abutments I and *3 of the driven shaft 5. The drivencollar It now drags the spring 53' inthe contracting direction, and the drag of the spring on element 2| is sufiicient to cause the spring l3 to contract to slight engagement with the stationary element 2|. In like manner counter-clockwise rotation of the shaft I is transmitted to the collar I! through the teasing lug 4' on driving lug 2, resulting in contraction of the springs and a driving engagement between the driving lugs 2, 3 and the abutments l, 8 in the manner described but in the opposite direction.

When rotation of the driving shaft has ceased, the resulting position of the driven shaft is secured against backlash by the close fit of the driven anchoring collar ID on the inner ends of the springs. The springsl2, [3 are wound in the same direction with reference to a continuous line along the shaft and hence in opposite directions outwardly from the intermediate collar Iii. Since the springs are expanded against the stationary element 2| when the shaft I is not being driven, any tendency of the driven shaft 5 to backlash in either direction will turn one spring or the other, through the attached collar ID, in the expanding direction and thereby increase the braking friction between that spring and the stationary element.

For the purpose of enabling assembly of the device from one end of the driven shaft, the lugs 4 and 4 are preferably detachably mounted in the driving lug 2. The positions of the lugs circumferentially in the notches 2!] can be regulated by means of the eccentric location of the lugs on the circular and rotatably adjustable plugs 28 secured by screws 29.

While a specific embodiment of the invention has been shown and been described, it will be understood that various alterations may be made without departure from the spirit of the invention as indicated by the appended claims.

What I claim is:

1. In a spring clutch device, a driving shaft and a driven shaft, a spring coiled on said driven shaft and having one end anchored to said driven shaft, and a driving connection between said driving shaft and the other end of said spring, said connection including a plug rotatably adjustable in the surface of said driving shaft and a lug positioned eccentrically on said plug and projecting outwardly therefrom.

2. An anti-backlash device comprising a driving shaft and a driven shaft, an abutment on the driven shaft adapted for engagement by a portion of the driving shaft on rotation thereof in a given direction, a helical spring on one of said shafts and having one end anchored to said driven shaft, a fixed enclosing member against which said spring is expanded when said shafts are at rest, said spring being coiled from said anchored end in said direction of rotation, and a driving connection between said driving shaft and the other end of said spring and operable only in said direction of rotation, whereby said connection releases said spring from said enclosing member when the driving shaft is rotated in said given direction, said connection including a plug rotatably adjustable in the surface of said driving shaft and a ing positioned eccentrically on said plug and projecting outwardly therefrom.

3. An anti-backlash device comprising a driving shaft and a driven shaft, abutments on said driven shaft adapted for engagement by portions of the driving shaft on rotation thereof in either direction, a pair of alined helical springs on one of said shafts and each having one end anchored to said driven shaft, said springs being coiled respectively in opposite directions from their anchored ends, a fixed member enclosing said springs, said springs being expanded against said 5 member when said shafts are at rest, and a driving connection between said driving shaft and the other end of each spring and operable on each spring only in the direction in which the spring is coiled from its anchored end, whereby to contract one of said springs in one direction of rotation and contract the other spring in the other direction of rotation of said driving shaft, each such connection including a plug rotatably adjustable in the surface of said driving shaft and a lug positioned eccentrically on said plug and projecting outwardly therefrom.

4. An anti-backlash device comprising a driving shaft and a driven shaft, abutments on said driven shaft adapted for engagement by portions of the driving shaft on rotation thereof in either direction, a pair of alined helical springs on one of said shafts and each having one end anchored to said driven shaft, said springs being coiled respectively in opposite directions from their anchored ends, a fixed member enclosing said springs, said springs being expanded against said member when said shafts are at rest, and a driving connection between said driving shaft and the other end of each spring and operable on each spring only in the direction in which the spring is coiled from its anchored end, whereby to contract one of said springs in one direction of rotation and contract the other spring in the other direction of rotation of said driving shaft, each such connection including an adjustable means for angularly positioning the connection with respect to the spring end.

5. In a spring clutch device, a driving member, a driven member, a spring coiled on said driven member with one end anchored to said driven member, a driving connection between said driving member and the other end of said spring, and means for adjusting the angular position between said driving and driven members at which said driving connection operates on said spring. I

6. In a spring clutch device, a driving shaft, a driven shaft, an abutment on said driven shaft arranged to be engaged by a portion of the driving shaft at a relative angular position of the two shafts upon rotation of the driving shaft in a given direction, a helical spring on one of said shafts having one end anchored to said driven shaft, a fixed enclosing member against which said spring is expanded when said shafts are at rest, said spring being coiled from said anchored end in said direction of rotation, a driving connection between said driving shaft and the other end of said spring and operable only in said di- 0 rection of rotation whereby said connection releases said spring from said enclosing member when the driving shaft is rotated in said given direction, and adjustable means for causing said driving connection to become operative at a predetermined angular relationship with respect to said relative angular position of engagement of said driving and driven shafts.

7. An antibacklash device comprising a driving shaft, a driven shaft adapted to be engaged by a portion of the driving shaft upon rotation of the driving shaft in a given direction, a spring coiled about one of said shafts in the said given direction of rotation with one end connected to said driven shaft, a fixed member against which said spring is expanded when said shafts are at rest,

a driving connection between the driving shaft and the other end of said spring acting upon rotation of the driving shaft in said given direction to release said spring from said fixed member, and means for adjusting the angular relation between said spring and said driving connection.

8. An anti-backlash device comprising a driv-- ing shaft and a driven shaft, abutments on said driven shaft adapted for engagement by portions of the driving shaft on rotation thereof in either direction, a pair of alined helical springs on one of said shafts and each having one end anchored to said driven shaft, said springs being coiled respectively in opposite directions from their anchored ends, a fixed member enclosing said springs, said springs being expanded against said member when said shafts are at rest, and a driving connection between said driving shaft and the other end of each spring and operable on each spring only in the direction in which the spring is coiled from its anchored end, whereby to contract one of said springs in one direction of retation and contract the other spring in the other direction of rotation of said driving shaft, and ad justable means for angularly positioning the connections with respect to the spring ends.

9. An anti-backlash device comprising a driv ing shaft and a driven shaft, abutments on said driven shaft adapted for engagement by portions of the driving shaft at some relative angular position of the two on rotation thereof in either direction, a pair of alined helical springs on one of said shafts and each having one end anchored to said driven shaft, said springs being coiled respectively in opposite directions from their anchored ends, a fixed member enclosing said springs, said springs being expanded against said member when said shafts are at rest, and a driving connection between said driving shaft and the other end of each spring and operable On each spring only in the direction in which the spring is coiled from its anchored end, whereby to contract one of said springs in one direction of rotation and contract the other spring in the other direction of rotation of said driving shaft, and adjustable means for angularly positioning the connections with respect to said angular positions of engagement of said driving and driven shafts,

10. An anti-backlash device comprising a driving shaft and a driven shaft, abutments on said driven shaft adapted for engagement by portions of the driving shaft on rotation thereof in either direction, a pair of alined helical springson one of said shafts and each having one end connected to said driven shaft, said springs being coiled respectively in opposite directions from their said connected ends, a fixed member enclosing springs, springs being expanded against said member when said shafts are at rest, and a driving connection between said driving shaft and the other end of each spring and operable on each spring only in the direction in which the spring is coiled from its connected end, whereby to contract one of said springs in one direction of rotation and contract the other spring in the other direction of rotation of said driving shaft, and means for adjusting the angular relation between each spring and its driving connection.

11. In a spring clutch device, a driving member, a driven member engaged by the driving member at a relative angular position of the two members upon rotation of the driving member in a given direction, a spring coiled on said driven member with one end anchored thereto, a driving connection between said driving member and the other end of said spring, and means for adjusting the angular position between said driving and driven members at which said driving connection operates on said spring.

WILLARD C. SWIFT, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

